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Lesson XIT. 

 MUSCLE (Concluded). 



(a) Nerve-Ending in Voluntary Muscle. 



Small pieces of the iiileivostal iimscles of a snake (the inter- 

 costal or any other ?;hnrt muscle of a small manunal may be used) 

 were placed for 10 to 15 minutes in filterei lemon juice, then luistiiy 

 washed in distilled water, transferred to a \% gold cidoride solution 

 for 15 to 20 nunutes, again washed in water, and placed in 20% for- 

 mic acid solution where they remained (protected from the light) 

 24 to -IS hours. Tease in glycerine. 



Study first under low powcn-. and search for a nerve 

 fibre terminating; in an end })late, Tlie nerve fibre and 

 the branched ending have a })urjjlish color, the muscle a 

 reddish imrplc Sketch under liigh power. 



(b) Isolated Heart Muscle Cells. 



Small pieces of the cardiac miiscle of a dog were macerated in 

 a 30% solution of caustic iiotash for 15 minutes; the maceration was 

 then interrupted by placing the tissue in a saturated acqueous 

 solution of i^otassium acetate. Tease in gum glvceiine. 



Observe tlie short oblong cells, one end usually 

 ])ranched. The cells show a cross and longitudinal stria- 

 tion, and possess one, occasionally two, oval nuclei. Draw 

 several as seeh under higli })ower. 



(c) Section of Heart Muscle. 



A small piece taken from the ventricle of a dog's heart was 

 hardened in a saturated acjueous solution of mercuric chloi'ide, 

 stained in Delafield's htematoxylin, embedded in paraffin, and 

 sectioned. Fix to slide, and mount in lialsam. 



Study under high power. Note how the cells are 

 cemented into fibres, and these into anastomosing bundles. 

 In cross sections of the muscle tlie nuclei are seen occupy- 

 ing the center of the cells. Sketch as seen under high 

 power. 



